Generally, downhole tools used in the formation of boreholes (e.g., wellbores) in subterranean formations are subjected to elevated temperatures and pressures. For example, downhole tools used in water, oil, and gas wellbore formation are subjected to temperatures that frequently exceed 100° C. Downhole tools used in geothermal wellbore formation can be subjected to temperatures reaching 350° C. and greater. The strength of materials generally decreases with increasing temperature. Thus, downhole tools may be damaged and may even experience catastrophic failure due, at least in part, to the weakening of the materials of the downhole tools with increased temperatures.
This temperature-induced weakening of materials in the downhole environment may require the use of costly materials that are difficult to manufacture and manipulate to ensure that the downhole tool including that material retains sufficient strength to operate even when subjected to high temperatures and pressures that weaken the material. In addition, temperature-induced weakening of materials may require a downhole tool operator to reduce the power acting on the downhole tool to prolong its life (i.e., to derate the downhole tool). For example, an operator may decrease weight-on-bit (WOB), torque on a drill string, speed of rotation of an earth-boring drill bit, or any combination of these as greater depths expose the earth-boring drill bit and components of the drill string to ever increasing temperatures and pressures. Wireline tools, which are lowered into a well on a wireline after drilling are used to determine characteristics of earth formations in the well. Such wireline tools may comprise a hollow, tubular pressure housing containing sensors and their electronics. With increasing temperatures, the highest pressure rating of these tools is reduced to avoid a possible collapse of the pressure housing and corresponding catastrophic tool failure. Any of the foregoing deratings of downhole tools may prolong the useful lives of the downhole tools despite temperature-induced weakening of the materials included in the downhole tools, but may also reduce a rate at which the downhole tools perform their tasks (e.g., reduce rate of penetration for an earth-boring drill bit), cause the downhole tool to perform abnormally, or reduce the maximum pressure at which the tool can be operated.